Looper-thread-controlling mechanism for sewing machines



G. S. GATCHELL. LOOPER THREAD CONTROLLING MECHANISM FOR SEWING MACHINES.APPLICATION FILED FEB. 6,19 19 1,40 ,1 5, I mm Feb. 28, 1922.

3 SHEETS-SHEET l- INVENTOR WlTNESSES:

G. S. GATCHELL.

LOOPER THREAD CONTROLLING MECHANISM F0 R SEWING MACHINES. APPLICATIONFILED mm, 1919.

1,408,1 5, Patented Feb. 28, 1922.

3 SHEETS-SHEET 2.

WITNESSES:

Y/ W v ORNEY I e. s. GATCHELL; LOOP ER THREAD CONTROLLING MECHANISM FORSEWING MACHINES.

APPLICATION FILED FEB--B, I919.

3 SHEETS- SHEET 3.

YatenteMieb. 28, 1922.

INVENTOR HLW 7 WITNESSES:

ATTORNEY UNITED s'rArp PATENT OFFICE.

GEORGE s. GATCHELL, or ROSELLE PARK, NEW a'nnsny, ASSIGNOR. To THE SINGMANUFACTURING COMPANY, A CORPORATION OFYNEW JERSELOOPER-THREAfD-CONTROLLING IJZECHANISM FOR SEWING- IMACHINES,

Application filed February 6, 1919, Serial No. 275,296.

To all whom it may concern:

Be it known that I, Gnonen S. Gn'rorrnnn,

a citizen of the United States, residing at Roselle Park, in the countyof Union and State of'N'ew Jersey, have invented certain new and usefulImprovements in Looper- 'lhread-Controlling Mechanisms for SewingMachines, of which the following is a specification, reference being hadtherein to the accompanying drawings.

In the formation of chain-stitch seams by machines of the well knowntype embodying a threaded vlooper in cooperation with one or morereciprocating needles, as disclosed,

for example, in U. S. patents to Muther etaL, No. 299,569 (one needle)and No. 583,- 415 (two needles), and Molyneux No. 1,- 266,036, (fourneedles), it is desirable from the standpoint of good sewing that theneedle-loops be fully drawn up to the. under surface of the workregardless of variations in the length of stitch or character of workbeing sewed.

needle-loops at the under side of the seam be uniform under varyingsewing condi tions. p

The looper of machines of the type under consideration commonly passes aloop of looper-thread through one or more needleloops and then presentsthe looper-loop for entry by the succeeding needle-loop or loops which,in turn, is or are entered by the looper carrying a new looper-loop, andso on. Vhenthe needle-loops are drawn up, the looper-thread is drawninto its usual circuitous or zigzag course through and about theneedle-loops, and it will thus be clear to those skilled in the artthat, other conditions being equal, a greater length of looper-threadwill be required for a long stitch than for a short stitch.

In operating machines of the above type,. it is customary at times tochain off, that v In other words, it is desirable that the appearance ofthe looper-thread and ,needlethread take-up means.

of an elastic nature and the feeding element WlllCll engages the chainin rear of the sew ing point will stretch the chain'thus allowing thestitches being formed to crowd more closely together on the usualstitch-supporting tongue or tongues in the throat-platc, than they wouldif formed in material.

Adjustment of theneedletlnead tension device will have a greater or lesseffect upon the degree to which the needle-loops are drawn up by theneedle-thread take-up mechanism and, while it is desirable to adjusttheneedle-thread controlling mechanism so that theneedle-loops will befully drawn,

up to the under surface of the work, itis a fact that if for any reasonthese loops are notfully drawn up, less looper-thread is required perstitch. I i i Thus the amount of looper-thread use per stitch dependsupon the stitch length and whether the machine is sewing in ma terial orchaining off, as well as upon other more or less variable conditions,such as the adjustment of the thread tension and It hasheretofore beencommon to provide machines of the type referred to with looper threadcontrolling mechanism comprising an intermittently acting thread-nipper,a pulloff on the supply side of the nipper and a take-up or slack-threadcontroller on. the I work or looper side of the nipper. In thesemachines, the looper starts forward to enter the needle-loop or loops,the looperthread is supposed to be free from slack and the take-up isdesignedlto have sufficient actron on the looper-thread to prevent theformation of slack as the looper advances, I

thereby overcoming the tendency of the looper-thread to buckle in frontof the eye of the looper. As soon as the looperbeak hasenter ed theneedle-loop or" loops,

the nipper is opened, and as the looper'advances to the end of itsstroke it draws through the nipper an amount of looperthread sufficientfor the formation of the next stitch; this amount having been previeuslvmeasured from the supply by the mil-off. As the Mr retracts the needles,1 i descend in the customary manner, pass1ngdown beside their previouslyformed, loops on the looper and entering the looper-loop.

After the looper has shed the needle-loop ioo or loops and nears the endof its retracting or chaining off.

stroke, the needle-thread take-up mechanism draws up or tightens theneedle-loop or loopswh'i'ch' thereupon absorb or draw into thestitchthei supply of slack looper thread afforded by the looper Thus,when the looperreaches the end of its retracting stroke, thelooper-thread is free from slack.

While itis possible to sew under these con ditions, the results from apractical standpoint are not fully satisfactory, inasmuch as the usualvariations in sewing conditions are'not taken care of. ForeXamp'le,"when the feed is shortened, or when chaining off,

less looper-thread is required perstitch, and the f amount oflooper-thread drawn past .the nipper by the advancing looper is morethan enough for the stitch being formed. As a result, there is slack inthe looperthread after the looper has reached the end ofitsretractingstroke and, as the looper starts forward, the take-up does not have.sufficient action to absorb this slack-thread and, in addition, takecare of the slack thread normally given up by the looper during the,first part of its advancing stroke. Thus, there is danger that thelooper-thread will buekle'in front of the eye of the looper and get onthe wrong or front side of the looper point, thus causingthread-breakage or skipping of stitches.

In. other words, the looper-thread controllin mechanisms" of the priorart will properly" control the looper thread only under-one fixed setofconditions. If, then, the feed is shortened or an attempt is made tochain off, the machine is very apt to break thread or skip stitches. Onthe other hand, if the feed is lengthened, the fixed amount ofslacklooper-thread afforded per stitclr will not permit the needle-loops tobe fullydrawnup and the appearance of the stitch will be unsatisfactory.

Further objectsof the inventioniwill ap; pear'from the followingdescription and claims.

To the" attainment of the ends in view, the stroke of the looper ispreferably made sufficient to draw enough looper-thread through thenipper for maximum requirements, that is, when sewing the longeststitches for which the machine is adapted, and the pull-offis designedto be-eapable-of measuring this amount of threadfrom the sup ply. Thenipper, instead of being timed as heretofore "to release the looperthread only during the last part of the advancing stroke of the-looper,is further timed to release the looper-thread momentarily just after theneedle-loops have been drawn up, which usually occurs at the time theloopers are fully down and the looper fully retracted.

In the present instance the relation of the pull-off to the nipper is afeature of great, importance; the pull-off being preferably so timedthat it is pulling thelooper-thread rather rapidly from the supply atthetime i of the momentary release of the looperthread by the nipvper. Theresult is that whatever slackth'read there may be between the nipper andthe work, as the looper is just starting forward, will be quickly pulledback through the nipper by the pull-off before the looper has travelleda material distance. In other words, any surplus or leftoverlooper-thread from the last stitch forming operation will be drawn backtothe supply side of the nipper by the pull-off, prior to the nextstitch-forming operation. .Thus the looper-thread will be free fromslack as the looper advances, whether or not the supply of looper-threadpulled forwardly through the nipper is fully absorbed in the laststitch.

The invention will be more particularly explained in connection with theaccompanying drawings in which Fig. 1 is a left side elevation of amachine embodying the invention. Fig. l is a perspective View of astructural detail of the looper-driving mechanism. Fig. 2 is ahorizontal section through the standard of the machine at an elevationabove the work-arm, showing thelatter inplan. Fig. 3 is a plan view ofthe throat-plate and feet -dogs. Fig. 4 is a diagram illustrating therelative timing of the. needle, looper, looper thread take-up,looperthread pull-off and looper-thread nippjer. Figs. 5, 5, 5 and 5illustrate the positions of the pull-off cam, nipper-cam,take-up cam andstitclrforming implements, respectively,

at the period of the cycle when'the needles Y are fully down. Figs. 6,6*, 6" and 6 are simi.- lar views at the period whenthe needles arerising aftenthe advancing looper has entered the needle-loops. Figs. 7,7h 7, and

7 are similar 'views at. the period ofthe cycle when the needles are upand the looper is at the end of its advancing stroke. Fig. 8 is a detailperspective of the supporting bracket for the ta re-up thread-guides andthe nipper-springs and Figs. 9 and 10 are plan and longitudinalsectional views seam made by the machine.

While the invention is susceptible of em of the end of the looper-shaft.

bodiment in chain-stitch machines generally, irrespective of the numberof needles employed or the type of the machine frame, I have chosen forthe purpose of thisdisclosure to embody it in the four-needle,singlelooper feed-up-the-arm machine disclosed in my copendingapplication Serial No. 185,

14:6, filed August 10, 1917.

As more fully disclosed in said copending application, the machineframecomprises the base 1 from which rises a hollow standard 2, carrying thebracket-arm 3 terminating in the head 4 within which are mounted theusual reciprocating needle-bar 5 and presser-bar 6. In the presentinstance, the needle-bar 5 carries four needles 7 and the presser-bar 6carries the presser-foot 8.

Supported at its rearward end by the standard 2 is the hollowwork-supporting arm 9 carrying at its forward or free end a throatplate10 and end-cap 11 within which is housedthe threaded looper 12. Thelooper 12 is mounted on the forward end of the looper-shaft 13 extendingwithin and longitudinally of the-work-arm 9 and receiving oscillatorymovements from an eccentric 1 1 on the main-shaft 15 through a pitman 16and crank 17. Endwise sliding movements are imparted to the looper-shaftby means of an eccentric 18 which is embraced by the strapped end of apitman 18 the opposite end of which is connected to the upstanding arm19 of a rock-lever fulcrumed upon but rocking independently of the shaft20. The depending arm. 21 of said rock-lever is connected by a link 22to a ball 23 at the rear The eccentrics 11 and 18 on the main-shaft thusoperate to impart the usual endwise reciprocatory and sidewise movementsto the looper.

The needles 7 and looper 12 cooperate in the usual manner common tomachines of this type to form the seam illustrated in Figs. 9 and 10wherein the abuttededges of material a, a are shown as being penetratedby the needle-loops Z2 which at the under side of the work areconcatenated with the looper-thread c in a well known manner.

The feeding mechanism may be of any usual type but is preferablyconstructed substantially in accordance with the disclosure of my saidcopending application. The

imparted to the feed-bars by means of the the slotted feed rocker-arms33 and 34 actuadjustable link connections 31 and 32 with 1' ated bymeans of the pitman connection 35 with the main-shaft. It will be notedthat.

the link 32 may be adjusted in the rockerarm*3t' by a treadleconnection, while the machine is in operation; the treadle connectioncomprising a chain 36, lever 37, 37 pivoted at 37*, a spring 38 and link39. The

main feed may be adjusted by shifting the rear end of the link 31 alongthe slotted feed-rocker 33, as will be readily understood.

Referring to Fig. 3 it will be seen that the I main feed-dog 25 includestwo sections 25 which are directly in rear of the usualstitch-supporting tongues 40 on the throatplate 10. The feed sections 25operate to engage the stitched seam and feed it away from the needles.When chaining off the feed-sections 25 engage the chain and pull it offof the tongues 40 on which it is formed.

The machine is equipped with needlethread take-up cams 411 which take upor tighten the needle-loops as they are shed from the looper and controlslack in the thread-nipping devices has beenmodified in certainimportant particulars as will be hereinafter explained. Journaled within7 and crosswise of the work-supporting arm 9 is a shaft 12 carrying agear 43 which meshes with a gear 44 turning upon the fixed studshaft 45;the gear 44 meshing with the driving gear 4L6 on the main-shaft 15. Thegear ratios are so chosen that the shaft 42 is driven at the same speedas the main-shaft.

Mounted on the shaft e2 are thepull-ofi and take-up cams 17 and 48,respectively, and the nipperactuating cam d9. The takeup cam comprises apair of spaced cam-disks between which is supported the usual castf oii50. Mounted on the bracket '56 at 51 is the thread-guiding fork 51, thetines of which are apertured at 52is provided to" present thelooper-thread to the action of the take-up cam. The pull-ofi cam 17 c0-operates in a similar manner with the castoff wire-55 and thethread-guiding fork 53, the tines ofwhich are apertured at 54. The

nippenoperating cam 49 acts upon a pair of superposed nipper-springs 55carried by the bracket 56 which supports the thread-guid ing fork 51.

The looper-thread travels its, usual course from one of the tensiondevices 6 on top of the bracket-arm. down through the tube57, throughthe guiding apertures 54 of the pull-off fork 53, thence between thenipper- :trated in Figs. 4 to '7, inclusive.

springs 55 and through the apertures 52 0t theitaker-upi fork '51,thence into the thread receiving slit 58 extendinglengthwise of thework-arm, and out through the guide 59 at tl1e-front end of thework-arm. :From the the looper-thread by the hump.- (iO, Fig. 7, of

the camylfi); at which time the needles arebeginning their descent andthe looper is beginning.itsu'eti'actingstroke. With the nippersprings:closed, the take-up 48 rapidly absorbsetheslack-thread afforded by theretractinglooper as the' main-shatt turns from 15 to 90 The came?islfpreferablyformed with a hump 61, Fig. 7 which operates, say, from.80 to 1209 to pull some thread from the sizipply but not enough for thenext stitch.

It isde'sirzlble, though not essential, that the pull ofi actzatthistime to permitot' a reductionyot theamplitude ofpull-oil action at alater period ot'the cycle, whereby abrupt or harsh cam actions on thelooper-thread may be avoided.v From 90 to 180 the takenp as gives upthread to the looper and to the contracting needle-loops which have beenshedby the looper. At 180 the needles are down, theloo fieriis attherearend of its strokegandfthe needle-loops shed from the looper are.fully; drawn up, thereby having absorbedinto theestitch-a sup-ply oflooperthread given up. by the takeup.

* At.- or slightly before the 180 point, a

rapid pull off action begins, see also Fig. 5, andncontinuesto the250point, Fig. 4, At, or just after-the beginning. of thisrapid pulloffaction', and just as the looper is starting forward, but before itihastravelled amatel'ialxlistance, the nippei springs 55? are permittecl=t0-openfor a brief interval, from 185 to 205, Fig. 4, so-that the pull-oill? ma fl draw. back through the 'nipper-springs .55 any slackor unusedlooper-thread remaining on the looper side otthe nippersprings after thelast stitch has been completely" drawn up by the needle-thread take-updevices; This pulling back of the unused or slack looper-threadregardless of theamount thereof, prior to the seizure of the newneedle-loops, permlts the next stitch-forming operation to be invariablybegun under the same conditions as regards 1 the looper-thread.

In other words they looper-thread will invariably be free from 1 slackas the looper begins its advancing stroke. Thiswillbe so regardlessoftheadjustment of the feed or any other of the usual variation 111sewing COHClIlJIOIlS.

will alwayshave sufficient, action (225 to As. a. result the hump 48 ofthe; take-up cam 48 255, Fig. 4) to prevent the bucklingotithew Ilooper-thread in front of the eye ofthe looper and the consequent threadbreakage or skipping of stitches. If a partial supply.

of thread for a stitch is not pulled ofi While.

the looper is retreating it will be necessary to pull off a full stitchsupply while the main.

shaft turns say from 180 to 255, Figa 4.

The pull-oil curve representing this period would therefore be steeper.

After the pull-off has. measured enouglu threadfrom the supply tomeet.the 1naxi-.

mumrequirements for; a new stitch -(260.

and the pull-off rapidly gives up looper thread to the advancing.looper, Fig. 6',

which in travelling to the end of, its strokei,

Fig. 7, pulls through the nip per and takeup enough.loopenthread for thelongest stitch which the machine is designed to make; After the looperretracts and the needle-loops are tightened, any, surplus looper-threadis pulled back through the nipper by the pull-off at the period of thecycle when the looper. is substantially at the end oi itsretracting.stroke and beforeit has I travelled a. material distance toward theneedles. Although preferable, it is not neces sary that the nipperbeclosed afterthe surplus. looper-thread has been pulled back. throughthe nipper by the pullsoff. The pull-off could be depended upon at'thistime; to prevent thebuckling of thelooper-thread in front of the eyeot'the looper as the looper 'advancesto seize the. needle-loops event. thehump lS of the take-up which according to Fig. Lacts upon thelooperthread from the 210 point to the 255? point In this I couldbedispensed with. lVhilethe-timing is broadly important, the detailsthereof are susceptible of considerable variationfwithin the scope oftheinvention as defined in the claims.

The invention ,notto be understood. therefore, as limited .to the exactconstrue tion shownand described, asthe principle thereof-1s obviouslysusceptlble of embodiment in var ous types of chain-stitch machines andin connection with various types of pull-off, take-up, andthread-nipping devices; the specific character and exact timing ofsuchdevices being unessentialso long as the general relationship andtiming is such that the unused looper thread is pulled back to thesupply side of the nipper, whereby the next stitch is invariably begununder the same conditions as regards the looper-thread.

Having thus set forth the nature of the invention, what I claim hereinis 1. Looper-thread controlling mechanism for sewing machinescomprising, one or more needles, a looper, means for imparting advancingand retracting movements to the looper, an intermittently actingthread-nipper, and means for pulling back to the sup ply side of thenipper any slack or unused looper-thread remaining on the work side ofthe nipper after the stitch has been drawn up.

2. Looper-thread controlling mechanism for sewing machines vcomprising,one or more needles, means for drawing up the needle-loops, a looper,means for imparting advancing and retracting movements to said looper, alooper-thread take-up, a pull-off, an intermittently actingthread-nipper between said take-up and pull-off, said pullofi? beingconstructed and timed to pull back through the nipper any surplus oflooperthread on the take-up side of the nipper after the stitch has beendrawn up.

3. Looper-thread controlling mechanism for sewing machines comprising,one or more needles, a looper, means for imparting advancing andretracting movements to said looper, a take-up, a pull-off, anintermittently acting thread-nipper between said take-up and pull-oil,said nipper being timed to open during the latter part of the advancingstroke of the looper to permit the looper to draw enough thread to reachthe end of its advancing stroke, said nipper being further timed to openafter the stitch has been drawn up and during the thread absorbingaction of the pull-off, to permit the pull-off to pull back any slackremaining in the looper-thread prior to the next stitch-formingoperation.

4:. In a sewingmachine, in combination, one or more needles, means fordrawing up the needle-loops, a thread-carrying looper, a looper-threadtake-up, an intermittently actin looper-thread nipper, and a looperthread pull off, the nipper being timed to permit the passage of thelooper-thread after the stitch has been drawn up, and the pull-oi?operating to pull back any surplus looper-thread remaining on the looperside of the nipper after the stitch has been drawn up, whereby thelooper-thread will be substantially tree from slack at the beginning ofthe next stitch-forming operation, re-

gardless of variations in sewing conditions.

of the looper at the end of its retracting stroke, and means for pullingback through the nipper any slack looper-thread remaining on the looperside of the nipper at the aforesaid time of release of the looperthread.

6. In a sewing machine, in combination, one or more reciprocatingneedles, means for drawing up the needle-loops, a thread-carrying looperhaving reciprocating loop-seizing and shedding movements, anintermittently acting looper-thread nipper, a looper-thread take-uptimed to take up the slack of the looper-thread during the first part ofthe retracting stroke of the looper, a pull-oil for measuringlooper-thread from the supply, said nipper being timed to open when thestitch is drawn up and during the action of said pull-off, whereby anyslack looper-.

thread on the work side of the nipper will be drawn back through thenipper by the pull-oil? prior to the seizure of the new needle-loop bythe looper.

7. In a sewing machine, in combination,

one or more needles, a looper, means for imparting advancing andretracting movements to said looper, a looper-thread takeup,looper-thread nipper, and a looperthread pull-off timed to pull off apartial supply of thread for the next stitch during the retractingstroke of the looper and the remainder of the supply during the advanceof the looper, said nipper being timed to release the thread while thepull-ofi is absorbing thread and prior to the seizure of needle-loops bythe advancing looper.

In testimony whereof, I have signed my name to this specification.

